1. Field of the Invention
Example embodiments of the present invention relate to a thin film layer, a heating electrode, a phase change memory including the thin film layer, and methods for forming the same. More particularly, example embodiments of the present invention relate to a method of forming a titanium aluminum nitride (Ti1−xAlxN) layer by atomic layer deposition (ALD) and a phase change memory device manufactured using the same.
2. Description of the Related Art
Typically, a thin film may be used as a dielectric layer of a semiconductor device, a transparent conductor of a liquid-crystal display, and/or a protective layer of an electroluminescent thin film display.
Thin films may be formed using a sol-gel method, a sputtering method, an electroplating method, an evaporation method, a chemical vapor deposition method, and/or atomic layer deposition (ALD). ALD may result in better step coverage than the chemical vapor deposition method. In addition, ALD may be performed at a lower manufacturing temperature.
A titanium aluminum nitride (Ti1−xAlxN) layer may be formed by ALD. Recently, the use of Ti1−xAlxN layer has increased due to its excellent oxidation prevention characteristics. If a Ti1−xAlxN layer is formed by conventional ALD, constituent of Al may be controlled by repeating the number of cycles in forming a TiN layer and an AlN layer or by controlling a reaction temperature. However, a deposition rate may be too low when employing these methods. Further, if Ti1−xAlxN layer is formed at a low temperature, a composition of the Ti1−xAlxN layer may change and constituent of impurities therein may increase, thereby decreasing the quality of the Ti1−xAlxN layer.
FIG. 1 is a schematic diagram of a conventional apparatus used to form a thin layer by atomic layer deposition (ALD).
Referring to FIG. 1, a thin layer forming apparatus may include a reaction chamber 11 that may be heated by an external heater (not shown), a substrate 13, for example, a silicon substrate, a susceptor 15 to support the substrate 13. The apparatus further includes a shower head 17 through which reaction gases may be injected onto the substrate 13. The reaction chamber 11 may further include a vacuum pump (not shown) used to control an interior pressure of the reaction chamber 11.
A shower head 17 may include a first shower head 17a and a second shower head 17b. The first shower head 17a may be connected to a first gas inlet 21, and the second shower head 17b may be connected to a second gas inlet 19. The first gas inlet 21 may be used to inject a nitrogen source, for example, NH3 gas into a reaction chamber 11. The second gas inlet 19 may be used to inject a titanium source, for example, TiCl4 gas, and an aluminum source, for example, TMA [Al (CH3)3] into the reaction chamber 11. It is understood that other types of source gases may be used. The above disclosed source gases are illustrated for example purposes.
Both the first gas inlet 21 and the second gas inlet 19 may be used to inject an inert gas, for example, Ar gas into the reaction chamber 11. Injection of Ar gas, TiCl4 gas, TMA, and NH3 gas may be controlled by a first valve V1, a second valve V2, a third valve V3, and a fourth valve V4, respectively.